Montys in strange places

'Here
is a photograph of the 'Montagu Swan', berthed on the floating pontoon
outside the Swan Hotel, Cornwall Beach, Plymouth in 1984. At
the time, many people asked: how had she got in there and how was she
going to get out again? Were there particularly low spring tides at the
time? We, of course, know the answer but you may like to offer up the puzzle to your readers.'